I have a common problem--mythtv seems to function normally, but trying to watch live TV or a prerecorded show fails with a blank screen and takes me back to the menu.

However, the problem is not due to a faulty tuner setup as the BlackScreenWatchingTV wiki page suggests. This is a frontend only, linked to a well-functioning dedicated backend. The frontend connects to the backend database, lists my recordings correctly, but cannot play them.

I've already been running a frontend on my Ubuntu desktop computer without problems, so I don't think backend configuration is the problem here.

This is the output when I run mythfrontend on my faulty machine:

2008-08-05 15:36:47.952 Using runtime prefix = /usr
2008-08-05 15:36:48.529 DPMS is disabled.
2008-08-05 15:36:48.529 Empty LocalHostName.
2008-08-05 15:36:48.530 Using localhost value of mythtv
2008-08-05 15:36:48.544 New DB connection, total: 1
2008-08-05 15:36:48.606 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:36:48.608 Could not open settings file /home/mythtv/.mythtv/config.xml for writing
2008-08-05 15:36:48.608 Closing DB connection named 'DBManager0'
2008-08-05 15:36:48.609 Primary screen 0.
2008-08-05 15:36:48.666 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:36:48.668 Using screen 0, 1920x1080 at 0,0
2008-08-05 15:36:48.685 New DB connection, total: 2
2008-08-05 15:36:48.743 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:36:48.748 mythfrontend version: 0.21.20080304-1 www.mythtv.org
2008-08-05 15:36:48.748 Enabled verbose msgs: important general
2008-08-05 15:36:48.879 Unable to parse themeinfo.xml for glass-wide
2008-08-05 15:36:48.879 The theme (glass-wide) is missing a themeinfo.xml file
2008-08-05 15:36:49.083 Unable to parse themeinfo.xml for glass-wide
2008-08-05 15:36:49.083 The theme (glass-wide) is missing a themeinfo.xml file
2008-08-05 15:36:49.375 No theme dir: /home/mythtv/.mythtv/themes/blootube-wide
2008-08-05 15:36:49.377 Primary screen 0.
2008-08-05 15:36:49.377 Using screen 0, 1920x1080 at 0,0
2008-08-05 15:36:49.378 No theme dir: /home/mythtv/.mythtv/themes/blootube-wide
2008-08-05 15:36:49.379 Switching to wide mode (blootube-wide)
2008-08-05 15:36:49.400 Using the OpenGL painter
2008-08-05 15:36:49.402 lirc init success using configuration file: /home/mythtv/.mythtv/lircrc
2008-08-05 15:36:49.406 JoystickMenuClient: Initialization of /dev/input/js0 succeeded using config file /home/mythtv/.mythtv/joystickmenurc
2008-08-05 15:36:50.425 Loading from: /usr/share/mythtv/themes/blootube-wide/base.xml
2008-08-05 15:36:50.465 Loading from: /usr/share/mythtv/themes/default/base.xml
2008-08-05 15:36:50.595 Registering Internal as a media playback plugin.
2008-08-05 15:36:50.700 MonitorRegisterExtensions(0x100, gif,jpg,png)
2008-08-05 15:36:50.761 Using NV NPOT texture extension
2008-08-05 15:36:50.850 MythMusic adding CD-Writer: 2,0,0 -- WDC WD800BEVS-00
2008-08-05 15:36:50.850 MythMusic adding CD-Writer: 5,0,0 -- BD-ROM BDU-X10S
2008-08-05 15:36:50.935 MonitorRegisterExtensions(0x40, ogg,mp3,aac,flac)
SIP listening on IP Address 192.168.1.35:5060 NAT address 192.168.1.35
SIP: Cannot register; proxy, username or password not set
2008-08-05 15:36:51.141 No theme dir: /home/mythtv/.mythtv/themes/blootube-wide
2008-08-05 15:37:03.660 XMLParse::LoadTheme using /usr/share/mythtv/themes/blootube-wide/ui.xml
2008-08-05 15:37:03.992 Connecting to backend server: 192.168.1.17:6543 (try 1 of 5)
2008-08-05 15:37:03.994 Using protocol version 40
2008-08-05 15:37:04.395 GetRecordBasename found no entry
2008-08-05 15:37:04.586 Using runtime prefix = /usr
2008-08-05 15:37:04.587 Empty LocalHostName.
2008-08-05 15:37:04.587 Using localhost value of mythtv
2008-08-05 15:37:04.602 New DB connection, total: 1
2008-08-05 15:37:04.664 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:37:04.666 Closing DB connection named 'DBManager0'
2008-08-05 15:37:04.724 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:37:04.726 New DB connection, total: 2
2008-08-05 15:37:04.784 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:37:04.789 Current Schema Version: 1214
2008-08-05 15:37:04.794 Can not locate recording made on '1041' at '20080805180000'
2008-08-05 15:37:04.799 Preview Error: Encountered problems running '/usr/bin/mythbackend --generate-preview 0x0 --chanid 1041 --starttime 20080805180000 '
2008-08-05 15:37:07.408 GetRecordBasename found no entry
2008-08-05 15:37:07.452 TV: Attempting to change from None to WatchingPreRecorded
2008-08-05 15:37:07.453 GetRecordBasename found no entry
2008-08-05 15:37:13.954 RingBuf(/myth/tv/): Invalid file (fd -1) when opening '/myth/tv/'.
2008-08-05 15:37:14.052 Unable to find image file: /myth/tv/.png
2008-08-05 15:37:14.240 Using runtime prefix = /usr
2008-08-05 15:37:14.241 Empty LocalHostName.
2008-08-05 15:37:14.241 Using localhost value of mythtv
2008-08-05 15:37:14.256 New DB connection, total: 1
2008-08-05 15:37:14.319 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:37:14.320 Closing DB connection named 'DBManager0'
2008-08-05 15:37:14.379 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:37:14.381 New DB connection, total: 2
2008-08-05 15:37:14.441 Connected to database 'mythconverg' at host: 192.168.1.17
2008-08-05 15:37:14.445 Current Schema Version: 1214
2008-08-05 15:37:14.449 Can not locate recording made on '1051' at '20080801170000'
2008-08-05 15:37:14.454 Preview Error: Encountered problems running '/usr/bin/mythbackend --generate-preview 0x0 --chanid 1051 --starttime 20080801170000 '
Destroying SipFsm object
2008-08-05 15:37:18.038 Deleting UPnP client...



Now, my installation is unusual. I set up a dual boot with Windows, so I manual-installed KM on /sda5, and I never made any provision for /myth, although it appeared anyway in the file system on the mysterious /hda3. I also followed the directions on the wiki for making KM a frontend.

But installation details shouldn't matter, because I have exactly the same problem when I use the CD as a frontend!

I'm particularly baffled because KM has run perfectly well on this hardware (minus the new hard drive) in a previous installation. The only thing I can think of is a weak network connection. I can ping the backend from my frontend, but the frontend can't seem to reach the Internet.

Any ideas?

I also get this problem with a frontend on the live cd: the screen goes blank and returns to the menu when you try and play a show from the menu.

I was thinking it might be a problem with getting the file to the frontend: possibly not being abe to read it off the mythbackend. But I haven't actually got a proper fontend / backend infrastructure so I'm not sure.

_________________
Running Knoppmyth R5.5 on a Compaq EVO D510 (sff) w/ P4 1.8GHz, 1GB RAM, 330GB 7200rpm Maxtor IDE HDD, XFX Nvidia GeForce 6200 (AGP low profile, p/n: PV-T44A-WANG) and Huappauge NOVA-T 500 DVB-T dual tuner PCI card.

I have this problem as well. Before, it worked just fine. I did a fresh install on my frontend only machine, and now it says it can't read the file for recordings. I mounted the backend's /myth to the frontend machine at /myth, but that didn't help any.

Another note, watching live TV does work from the frontend. I'm not sure why though...

Did you export the /myth partition with the right permissions and make sure that the FE machine had it mounted properly?

Also, have you tried the streaming option in the settings?

Well, after a few days, it works partially now. Fresh recordings seem to work, but recordings from before I upgraded the backend still do not. Another thing I noticed on the backend is the channel call sign got messed up during the upgrade. For instance, the USA channel now show as "USAEEEEEEEEEEEEESFW3" and channel number "39I8VZBZF" (it is on channel 39). I doubt that's the primary reason recordings fail to open, but it's part of the general fishiness.

I've fixed the db tables on that entry, time for some more testing.

Hi, I was wondering whether anyone has solved this yet?
I've finally taken the plunge to build a dedicated frontend only box with Knoppmyth R5.5 accessing a R5.5 combined frontend / backend machine. I installed R5.5 onto the box fine and then edited the mysql.txt file: /etc/mythtv/mysql.txt for my setup and also on the frontend when it first switched on. I also stopped mythtv-backend and mysql server from starting at startup: "update-rc.d -f mythtv-backend remove" etc. and I could view the recordings on the backend fine and also view an animated preview fine on the view recordings menu. Livetv also works ok but with choppy playback (I think this is the hardware on the frontend or a dodgy xorg.conf file which probably needs more work) and the tv guide works fine. However playing a recording causes the screen to blank and return to the recordings menu after a second or so. I don't think it can be a network issue or a graphics issue if livetv works fine and also the guide?

I haven't exported the myth partition at all but with R5F27 I never needed to and I have tried the streaming option in the settings but that made no difference.

Any help or advice would be greatly appreciated, thanks Mythman

_________________
Running Knoppmyth R5.5 on a Compaq EVO D510 (sff) w/ P4 1.8GHz, 1GB RAM, 330GB 7200rpm Maxtor IDE HDD, XFX Nvidia GeForce 6200 (AGP low profile, p/n: PV-T44A-WANG) and Huappauge NOVA-T 500 DVB-T dual tuner PCI card.

Not running 5.5 ATM, but I don't believe mounting /myth from your BE is necessary. Have you made the following changes in Setup on your FE?

Setup -> General -> 1st page - Host name: Should be set to your BE's IP address (or hostname)
Setup -> General -> 2nd page - Use custom identifier for frontend preferences & Custom identifier: These are used to uniquely identify the FE(s). Your KM boxes MUST use unique hostnames
(See http://knoppmyth.net/phpBB2/viewtopic.p ... p+frontend for additional information)

These are from an R5F27 install, they may be located somewhere else/named slightly differently in 5.5, but should get you going.

Hi slowtolearn,
Thanks for the pointers. I already had the frist implemented but not the custom unique indentifer. So I set this and rebooted the frontend but unfortunately the same problem persists (play recordings = blank screen then immediate return to menu). This seems really weird and I'm surprised many others haven't had this problem too...
If you or anyone has any more advice that'd be appreciated,
Thanks,
Mythman

_________________
Running Knoppmyth R5.5 on a Compaq EVO D510 (sff) w/ P4 1.8GHz, 1GB RAM, 330GB 7200rpm Maxtor IDE HDD, XFX Nvidia GeForce 6200 (AGP low profile, p/n: PV-T44A-WANG) and Huappauge NOVA-T 500 DVB-T dual tuner PCI card.

What does your /var/log/mythtv/mythfrontend.log reveal when you try to view a recording?

when the frontend starts up I get:

Then when I play a recording I get:

So it seems to be a file read problem.

Is there some standard firewall on the backend I don't know about that is blocking a connection to this port?

Thanks,
Mythman

_________________
Running Knoppmyth R5.5 on a Compaq EVO D510 (sff) w/ P4 1.8GHz, 1GB RAM, 330GB 7200rpm Maxtor IDE HDD, XFX Nvidia GeForce 6200 (AGP low profile, p/n: PV-T44A-WANG) and Huappauge NOVA-T 500 DVB-T dual tuner PCI card.

That doesn't seem right, it should say something along the lines of "Connected to database 'mythconverg' at host: <Your BE IP>"
But...

Possibly a time or timezone mismatch?

Hi slowtolearn, yes my timezone was incorrect so I changed that to the correct one using this site:
http://www.wikihow.com/Change-the-Timezone-in-Linux
I did chose the right one during setup it just seems to have defaulted back to PDT for some reason?!

This didn't solve the problem though and it still has the NVP error of being unable to read the file, except now it has codec information and an NVP prebuffer error. The mythtv error about connecting to the socket seems to have resolved itself though.

If you have any other ideas that'd be great,
thanks,
Mythman

_________________
Running Knoppmyth R5.5 on a Compaq EVO D510 (sff) w/ P4 1.8GHz, 1GB RAM, 330GB 7200rpm Maxtor IDE HDD, XFX Nvidia GeForce 6200 (AGP low profile, p/n: PV-T44A-WANG) and Huappauge NOVA-T 500 DVB-T dual tuner PCI card.

From what I gathered from the Google hits on "GetRecordBasename found no entry" the problem lies in a mismatch in time and/or timezone between the BE and FEs. Are your systems now all set to the same timezone, and show the correct time?

Guess you'll have to post another snippet of your log file, so we can see exactly what it's telling you...

I had the same problem on a laptop I was booting a livecd frontend for one-time use. I could see live tv just fine. I could see previews of recordings just fine. I just couldn't watch recordings.

I had booted and just skipped the time/timezone setting screen. I rebooted and entered the proper timezone and time and voila! Worked fine. No other settings were changed.

-Bill